On “Un” Frozen Ground

Thawing ground, or permafrost, is a potential troublemaker throughout the Arctic.

Permafrost is mostly frozen water in which ice crystals help bind it together. When the ice melts, the ground collapses.

Until recently, permafrost has been solid enough to support houses, highways, pipelines, and airfields. But rising temperatures have melted the frozen soil’s upper portion, compromising its capacity to bear weight.